A drive device configured to drive two driven parts such as a pair of arms includes a drive device having two coaxial rotary driving shafts. Such a conventional drive device is applied to a tool magazine. The tool magazine includes a rotating main table and a sub-table rotatably installed at a periphery of the main table. The sub-table is provided with a plurality of “tool pots” (a registered trademark) configured to attach and detach tools. The tool magazine rotates the main table and the sub-table independently of each other, thereby moving a desired tool pot to a takeout position.
In addition, the tool magazine has a cylindrical outer shaft and an inner shaft passing through an inner hole of the outer shaft, in order to rotate the main table and the sub-table independently of each other. The outer shaft and the inner shaft are driven by different motors, respectively. The main table is installed at the outer shaft. A sun gear configured to rotate the sub-table is installed at the inner shaft. The sub-table is driven by a planet gear rotating around the sun gear.
There is a demand for using the drive device having two coaxial rotary shafts as described above in low pressure conditions. In this case, it is needed to provide a configuration for separating a space at an atmospheric pressure from a space at a low pressure in the drive device.